Connecting two range extenders to a wireless router? Really need help

Somebody please please please help me, i am being driven to distraction trying to connect 2 sitecom wireless range extenders to a netgear router. I have literally tried everything i can think of and hve spent 20+ hours on this now with no success.

I currently have the netgear router set with an IP address of 192.168.1.1 with DHCP enabled and no security set up (i originally had WEP enabled but this made the problem worse.

I then have two sitecom range extenders set up connected to the router wirelessly to extend the signal in opposite directions. One is set up with an IP address of 192.168.1.2 and the other 192.168.1.3 with default gateway set at 192.168.1.1 and DHCP disabled. This sets the network up working for a short time however as soon as more than one machine tries to connect to the network it all shuts down. It seems that the setup cannot assign IP addresses to more than machine at a time.

Please can anyone help me i have really reached the end of my tether with it and have no idea where to go from here or what the problem may be.

cheers
Wattso